In every decade, parents are surrounded by hype and anxiety. Don’t make mistakes! Don’t mess up the kids! But parents ought to be growing more relaxed rather than more panic-stricken, as the latest news from the geneticists is: The nature/nurture debate is over, and nurture has lost. It’s all genetics! Identical twins separated at birth and located 35 years later show up as matching curly-haired biology teachers in size-nine shoes and capris, living in Midwestern states, one married to a man named Steve and the other to a man whose middle name is Stephen, and they both like dachshunds!

A one-out-of-a-hundred-billion twist of DNA, slotted into place at the moment of conception, plots a child’s course. Except for one thing. According to the scientists, parenting seems to make a difference in a person’s sense of optimism.

If that’s the only bone they’re tossing us, I’ll take it. Happiness, hope, and a can-do spirit can wreak miracles.

My husband and I, married for 34 years, have nine children: four by birth and five by adoption. One of our sons by adoption arrived in Atlanta from Addis Ababa, Ethiopia, in the summer of 2007, at age 13. A tall and gloomy fellow, Daniel had seen a lot of the worst that life can offer: a loving family splintered by HIV/AIDS, displacement from his village to an orphanage in the city, almost everything he’d known swept away. When, in our kitchen, his long narrow face lit up with laughter, it was a wonderful sight. But it was a brief one. His expression soon fell back to distaste. His first clearly enunciated English phrase was “Oh my God.”

“Oh my God” meant: This is a total disaster.

One afternoon that summer, I came home from the market and found him sitting on a blue Adirondack chair on the front patio, within the lacy shadows of the Japanese maple. He was curved into a posture of grief, cradling his face within his long-fingered hands.

“What’s wrong?!” I cried, setting down paper sacks of peaches, corn, and onions.

He looked up and said, “My life. Oh my God,” and returned his face to his hands.

“What’s wrong with your life?”

He looked up again with haggard eyes. “Helen,” he said, naming his new younger sister, an ebullient and sparkly girl of 11, “will not stop laughing.”

Contemplating where he’d been, the bleak future that had once loomed before him—homelessness in one of the poorest nations on earth—and the opportunities that were spread before him now, I couldn’t think of a reply. I collected the produce and went into the house. He’s not used to the presence of a lighthearted girl, I thought. Even the sound of feminine laughter rubs him the wrong way. Later I considered that the sound of merriment itself, regardless of gender, offended him as untrue. Laughter did not strike him as one of the world’s authentic sounds.